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Tinymovr May-June Update

A project log for Tinymovr Motor Controller

Affordable, precise, integrated motion control for robotics

yannisYannis 05/30/2021 at 20:080 Comments

Message from update author: I mistakenly forgot to publish this update and I just realized it now. Well, better late than never! Here it goes:

Presenting: The Tinymovr Trajectory Planner!

Video first:

We implemented a trapezoidal trajectory planner into Tinymovr, that runs at the 20kHz rate, for silky-smooth trajectory interpolation. The planner works in two modes: In acceleration-limited mode, you set the max acceleration and cruise velocity, and the planner derives the necessary travel times. In time-limited mode, you set the desired acceleration-cruise-deceleration times, and the planner derives the max acceleration, cruise speed, and deceleration values.

The planner is available through CAN Bus using the following commands:

tm1.plan_t_limit(target_pos, total_time, accel_percent, decel_percent)

The above command will initiate a time-limited trajectory with specified parameters. The accel_percent and decel_percent denote how much of the total move time will be taken by acceleration and deceleration. The scale here is 0-255, with 0-0% and 255-100%. This is a convenient mode if you wish to synchronize multiple axes of e.g. a cartesian machine. Alternatively, you can use a velocity and acceleration limited trajectory:

tm1.set_max_accel_decel(max_accel, max_decel)
tm1.plan_v_limit(target_pos, max_vel

The above will generate a trajectory that respects the limits in acceleration, cruise velocity, and deceleration specified.

The velocity-limited trajectory planner is also available through the UART protocol, where you can specify parameters one at a time with different commands:

Max acceleration:

.>50000

Max deceleration:

.<50000

Max velocity:

.^100000

 Plan and execute move to a position:

T-100000

 We hope this functionality extends the applications of Tinymovr, and can't wait to see how you apply it!

We'll be switching to bi-monthly updates for the duration of the summer, and re-evaluate afterward. See you in the next update!

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